1. Field of the Invention
The present invention pertains to endoscopic portals for establishing communication with an internal site in a body and, more particularly, to endoscopic portals having universal seals forming a seal with instruments of various sizes introduced through the endoscopic portals and to methods for introducing instruments through such universal seals.
2. Brief Description of the Prior Art
In endoscopic procedures, a portal, such as a sleeve or cannula or other structure forming a passage, is normally disposed in a cavity wall such that a distal end of the portal is positioned within the cavity and a proximal end of the portal is disposed externally of the cavity to provide a passage establishing communication with an internal site from externally of the cavity. Typically, various instruments are introduced at the operative site through the passage defined by the portal in order to perform diagnostic and/or surgical procedures, with the instruments many times having varying sizes in cross-section. In endoscopic procedures, it is important to prevent undesired fluid flow to and from the internal site; and, accordingly, the portal must be sealed prior to and subsequent to the introduction of instruments and while the instruments are in place. In particular, fluids such as gaseous phase carbon dioxide or nitrous oxide are normally introduced in the body for insufflation as part of the endoscopic procedure, and the escape of such gases through the portal should be prevented.
Many endoscopic portals have valves including a valve passage having a fixed size. Instruments larger in size than the fixed size of the valve passage cannot be inserted through the valve passage into the portal; and, when instruments smaller in size than the fixed size of the valve passage are inserted, fluid can escape past the smaller size instruments. Universal seals having variable size passages for receiving and sealingly engaging instruments of various sizes have been proposed for endoscopic portals. Many of the universal seals proposed for endoscopic portals are made of elastic, tearable materials, and instruments inserted through the variable size passages come in contact with the tearable materials. Accordingly, there is a risk that the seals may be torn or punctured when instruments are inserted or withdrawn, particularly where the instruments inserted are sharp. In order to avoid tearing by the inserted instruments, more rigid protectors have been disposed within the seals; however, such seals, even with protectors, still have the disadvantages of being opened by contact with an instrument to be introduced and, thus, creating an obstruction to introduction of the instrument and the opportunity for tearing of the seal causing undesirable leakage of gas. Additionally, prior art universal seals increase resistance to introduction and withdrawal of instruments due to contact of the instruments with the seal and can adversely affect the instrument being inserted by such contact.